Bionematicidal Effect of Verticillium leptobactrum Against Nematodes (Meloidogyne spp.) and Globodera Parasitic Complex on Potato (Solanum tuberosum L.)

In the search for alternatives to pesticides in managing phyto-parasitic nematodes, we investigated the nematicidal efficacy of Verticillium leptobactrum, as nematophagous fungus, towards two Root-Knot Nematodes (RKN) species Meloidogyne javanica and M. arenaria and Potato Cyst Nematode (PCN) Globodera rostochiensis, on potato cv. Spunta. An experiment was undertaken in vitro to estimate the effect of increasing dilutions (10, 25, 50, 75 and 100%) of fungal culture filtrate on the mortality of G. rostochiensis second-stage juveniles (J2), at different periods. After 48 h of exposure, the various dilutions of the filtrate showed nematicidal activity against G. rostochiensis and paralyzed the J2. The highest larval mortality (70%) was recorded with the pure culture filtrate (100%) after a 96 h exposure. In a pot experiment, fungal preparation (consisting of wheat kernel colonized by the antagonistic fungus) was mixed with soil at the rate of 10 g/kg soil (corresponding to 2.108 spores/g), and its nematicidal potential was compared with the commercial chemical nematicide “Vydate” (10 g/kg), against RKN and PCN infecting potato plants, under glasshouse conditions. V. leptobactrum isolate treatments reduced numbers of egg masses, galls and cysts on roots by respectively 88%, 73% and 50% compared to the control. RKN and PCN J2 density in soil also decreased by 93% and 30% respectively due to the fungal presence. When compared to the commercial chemical nematicide, V. leptobactrum was comparable or better in suppressing nematode populations in potato root systems. Furthermore, treatment with V. leptobactrum increased the growth parameters of potatoes compared with parasitized control. The results suggest that V. leptobactrum could be applied as an environmentally-friendly approach to Meloidogyne-Globodera disease complex management on the potato crop.